The intersection of Cesar Chavez and Evans Avenue is a good enough place to start. Face south.

Behind you is Potrero Hill, once a working-class neighborhood (and still home to a public housing project) where homes now sell for way more than a million dollars and rents are out of control. In front, down the hill, is one of the last remaining industrial areas in San Francisco.

Go straight along Evans and you find printing plants, an auto-wrecking yard, and light manufacturing, including a shop that makes flagpoles. Take a right instead on Toland, past the Bonanza restaurant, and you wander through auto-glass repair, lumber yards, plumbing suppliers, warehouses, the city's produce market — places that the city Planning Department refers to at Production, Distribution, and Repair facilities. Places that still offer blue-collar employment. There aren't many left anywhere in San Francisco, and it's amazing that this district has survived.

Cruise around for a while and you'll see a neighborhood with high home-ownership rates — and high levels of foreclosures. Bayview Hunters Point is home to much of the city's dwindling African American population, a growing number of Asians, and much higher unemployment rates than the rest of the city.

Now pull up the website of the Association of Bay Area Governments, a well-funded regional planning agency that is working on a state-mandated blueprint for future growth. There's a map on the site that identifies "priority development area" — in planning lingo, PDAs — places that ABAG, and many believers in so-called smart growth, see as the center of a much-more dense San Francisco, filled with nearly 100,000 more homes and 190,000 new jobs.

Guess what? You're right in the middle of it.

The southeastern part of the city — along with many of the eastern neighborhoods — is ground zero for massive, radical changes. And it's not just Bayview Hunters Point; in fact, there's a great swath of the city, from Chinatown/North Beach to Candlestick Park, where regional planners say there's space for new apartments and condos, new offices, new communities.

It's a bold vision, laid out in an airy document called the Plan Bay Area — and it's about to clash with the facts on the ground. Namely, that there are already people living and working in the path of the new development.

And there's a high risk that many of them will be displaced; collateral damage in the latest transformation of San Francisco.

CLIMATE CHANGE AND "SMART GROWTH"

The threat of global climate change hasn't convinced the governor or the state Legislature to raise gas taxes, impose an oil-severance tax, or redirect money from highways to transit. But it's driven Sacramento to mandate that regional planners find ways to reduce greenhouse gas emissions in California cities.

The bill that lays this out, SB375, mandates that ABAG, and its equivalents in the Los Angeles Basin, the Central Coast, the Central Valley and other areas, set up "Sustainable Communities Strategies" — land-use plans for now through 2040 intended to reduce greenhouse gas emissions by 15 percent.

The main path to that goal: Make sure that most of the 1.1 million people projected to live in the Bay Area by 2040 be housed in already developed areas, near transit and jobs, to avoid the suburban sprawl that leads to long commutes and vast amounts of car exhaust.

The notion of smart growth — also referred to as urban infill — has been around for years, embraced by a certain type of environmentalist, particularly those concerned with protecting open space. But now, it has the force of law.